A mold is necessary to manufacture a cast metal. Examples of the mold are a heat-curing mold, self-curing mold, and gas-curing mold. For example, the self-curing mold is generally manufactured by a method of filling kneaded sand containing a refractory granular material, hardener, and binder in a wooden model or resin model (to be collectively called “a model” hereinafter), and curing the binder. To manufacture a mold having a complicated shape, however, it is necessary to increase the number of models, and this complicates the process. Also, even when the number of models can be increased, no mold can be manufactured if the models cannot be removed from the mold.
To solve these problems, a mold manufacturing technique using three-dimensional lamination shaping capable of directly manufacturing a mold without using any model has been proposed. Three-dimensional lamination shaping is a method of manufacturing a mold by directly using a three-dimensional shape input on a CAD (Computer Aided Design) system as a stereomodel (three-dimensional model).
A known example of this mold manufacturing technique using three-dimensional lamination shaping is a method (two-component self-curing mold) of repeating an operation of laminating (recoating) kneaded sand obtained by mixing a refractory granular material and liquid hardener and printing a binder on the kneaded sand based on CAD data, and removing the kneaded sand from an unprinted portion after the binder is cured (see, e.g., patent literature 1).